1. Field of the Invention
The present invention relates to an improved structure for a tape measure, and more particularly to a tape measure equipped with a control apparatus which can control the extended tape to halt at any position during its withdrawal motion.
2. Description of the Prior Art
A tape measure is popularly used in domestic and engineering application, especially for civil and architectural engineering. Since it is so widely used for surveying, measurement, estimation and inspection, it is very important to develop a tape measure which can be handled simply, securely and conveniently.
The common disadvantages of a conventional tape measure usually experienced by the user are:
1. The extended tape with resiliency is apt to bounce back abruptly with a large spring restoring force if it is failed to be fixed at once. It often leads to a result of hurting the user or a third person staying nearby. PA1 2. The control apparatus for extension and withdrawal motion of a conventional tape measure has a high failure rate because of its poor durability with disturbance to the user. PA1 3. Because of the weakpoint described in above item 1, a conventional tape measure is difficult to operate conveniently for measuring several objects with different lengths successively. Once it fails to be halted at a predetermined position, the tape must be drawn out again that results in very low efficiency of measuring. PA1 4. The rapid withdrawing motion of the tape with strong spring restoring force may easily hurt the operator's finger by scraping his finger with the tape edge.
Presently, there were two patents U.S. Pat. No. 4,153,996 and 5,007,178, related to improved structure for tape measures. Although, a great deal of improvements were made to the structure and properties of the conventional tape measure, there are still more improvements that can be made for assembly, and operation.